Wild and Cultivated Apricot Genetic Structure Linked to Plum Pox Potyvirus Resistance

Apricot (Prunus armeniaca L.) is an important horticultural stone fruit species in the Northern hemisphere, where it is being severely threatened by Plum Pox Virus (PPV) infection (sharka disease). In a previous genome-wide association study (Mariette et al., New Phytologist, 2015), we identified PPV resistant apricot cultivars and mapped the resistance determinants. This work was completed, in the frame of the FP7 Marie Curie STONE project (#246795), by a search of the geographical origin and a world-wide genetic diversity analysis of resistance source(s) to sharka in apricot. Indeed, the apricot wild progenitor, P. armeniaca vulgaris, is still present as a forest tree in its native area, on the slopes of the Tien Shan range, where it co-occurs with the wild apple species, Malus sieversii. We thus investigated patterns of molecular diversity and genetic structure using microsatellite markers in a dataset of 380 wild apricot accessions collected in Central Asia, natural populations (Kazakhstan, Uzbekistan, Western China and Kyrgyzstan). They were compared with Western and Eastern cultivated relatives in order to determine putative geographic origin of European cultivated apricots and to reconstruct its evolutionary history. We observed high levels of genetic diversity in Central Asian and Chinese germplasm, in agreement with an origin of this species in this region. Lastly, we unraveled the origin of resistance to PPV and present here preliminary results on its phenotypic variability within the native apricot gene-pool, in comparison with European and North-American cultivated apricots.